CN112242245A

CN112242245A - Laminated ceramic electronic component and method for manufacturing laminated ceramic electronic component

Info

Publication number: CN112242245A
Application number: CN202010668165.1A
Authority: CN
Inventors: 大野亮; 福冈哲彦; 楠本昌司; 河野明彦
Original assignee: Taiyo Yuden Co Ltd
Current assignee: Taiyo Yuden Co Ltd
Priority date: 2019-07-16
Filing date: 2020-07-13
Publication date: 2021-01-19
Also published as: JP2024096307A; US11798745B2; US20210020379A1

Abstract

The invention provides a laminated ceramic electronic component capable of improving reliability and a manufacturing method thereof. A laminated ceramic electronic component includes: a functional section having internal electrodes laminated in a first direction; a covering portion that covers the functional portion from a first direction; and covering a side edge portion of the functional portion from a second direction orthogonal to the first direction. The functional portion has, in a predetermined cross section: a first linear portion adjacent to the covering portion and extending in the second direction; a second straight portion adjacent to the side edge portion and extending in the first direction; and a corner portion connected to the first and second linear portions. The corner portion is curved so as to satisfy the condition that a is not less than 1 [ mu ] m and 0.1 not less than a/b is not more than 0.4, where a is a distance in the first direction between a first virtual line extending in the second direction of the first straight portion of the corner portion and an end point on the first virtual line side of the second straight portion, and b is a distance in the second direction between a second virtual line extending in the first direction of the second straight portion and an end point on the second virtual line side of the first straight portion.

Description

Laminated ceramic electronic component and method for manufacturing laminated ceramic electronic component

Technical Field

The present invention relates to a laminated ceramic electronic component such as a laminated ceramic capacitor and a method for manufacturing the same.

Background

In recent years, with the miniaturization and high performance of electronic devices, there has been a strong demand for the miniaturization and large capacitance of multilayer ceramic capacitors used in electronic devices. In order to meet this demand, it is effective to enlarge the internal electrodes of the multilayer ceramic capacitor. In order to enlarge the internal electrodes, it is necessary to thin side edge portions for securing insulation around the internal electrodes.

Patent document 1 discloses a technique of adding a side edge portion later from the viewpoint of achieving a thinner side edge portion. In this technique, a ceramic protective layer (side edge portion) is provided on a side surface of a green sheet in a state where an internal electrode is exposed to the side surface.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2012-209539

Disclosure of Invention

Technical problem to be solved by the invention

However, in the technique described in patent document 1, when the side edge portions are thinned, sufficient moisture resistance cannot be obtained, and it is difficult to improve reliability.

In view of the above-described circumstances, an object of the present invention is to provide a laminated ceramic electronic component capable of improving reliability, and a method for manufacturing the same.

Technical solution for solving technical problem

In order to achieve the above object, one aspect of the present invention provides a laminated ceramic electronic component including a functional portion, a covering portion, and side edge portions.

The functional section has internal electrodes stacked in a first direction.

The covering portion covers the functional portion from the first direction.

The side edge portion covers the functional portion from a second direction orthogonal to the first direction.

The functional portion includes, in a cross section orthogonal to a third direction orthogonal to the first direction and the second direction, at a point where the functional portion is bisected in the third direction: a first linear portion adjacent to the covering portion and extending in the second direction; a second straight portion adjacent to the side edge portion and extending in the first direction; and a corner portion connected to the first linear portion and the second linear portion.

In the corner portion, when a distance in the first direction between a first virtual line extending the first straight portion in the second direction and an end point of the second straight portion on the first virtual line side is represented by a, and a distance in the second direction between a second virtual line extending the second straight portion in the first direction and an end point of the first straight portion on the second virtual line side is represented by b, the corner portion is bent so as to satisfy a condition of a ≥ 1 μm and 0.1 ≤ a/b ≤ 0.4.

In this structure, the functional portion has a corner portion bent so that a is not less than 1 μm and a/b is not less than 0.1 and not more than 0.4. By setting the corner portions to satisfy the conditions of a.gtoreq.1 [ mu ] m and a/b.gtoreq.0.1, the distance from the surface of the laminated ceramic electronic component to the end of the outermost internal electrode can be sufficiently ensured, and the deterioration of moisture resistance can be suppressed. Furthermore, the corner portion satisfies the condition that a/b is less than or equal to 0.4, thereby preventing the outermost internal electrode from being sharply bent. This can suppress short-circuiting between the internal electrodes adjacent to each other in the first direction. Therefore, according to the above configuration, moisture resistance deterioration and short-circuit failure can be suppressed, and a highly reliable multilayer ceramic electronic component can be obtained.

The thickness of the side edge portion may be 10 μm or more and 15 μm or less.

The thickness of the side edge portion may be 12 μm or less.

Thus, even when the thickness of the side edge portion is extremely thin, sufficient moisture resistance can be ensured. Therefore, a small, large-capacitance, highly reliable laminated ceramic electronic component can be obtained.

The corner portion may be curved inward in the first direction from the end point on the second virtual line side of the first straight portion toward the end point on the first virtual line side of the second straight portion.

Specifically, the functional portion may have 4 of the corner portions in the cross section.

A method for manufacturing a laminated ceramic electronic component according to another aspect of the present invention includes the following steps. And a step of laminating a third ceramic sheet, on which no internal electrode is formed, in the first direction on the first-direction outer surface of a laminate in which first ceramic sheets and second ceramic sheets are alternately laminated in the first direction, to form a laminated sheet, wherein the first ceramic sheets and the second ceramic sheets each have a plurality of internal electrodes formed thereon.

And a step of pressure-bonding the laminated sheet from the first direction.

A step of producing a laminated chip by dicing the laminated sheet, wherein the laminated chip includes: a functional portion having internal electrodes laminated in the first direction; a covering portion for covering the functional portion from the first direction; and a side surface exposed from the internal electrode and facing a second direction orthogonal to the first direction.

And forming a side edge portion on the side surface.

And forming a functional portion after firing by firing the laminated chip on which the side edge portion is formed.

The functional part after firing has, in a cross section orthogonal to a third direction orthogonal to the first direction and the second direction, a position bisecting the functional part after firing in the third direction, the cross section orthogonal to the third direction: a first linear portion adjacent to the covering portion and extending in the second direction; a second straight portion adjacent to the side edge portion and extending in the first direction; and a corner portion connected to the first linear portion and the second linear portion.

In the first ceramic sheet and the second ceramic sheet, the plurality of internal electrodes are arranged at intervals in the second direction with a non-electrode-forming region interposed therebetween.

In the step of pressure-bonding in the first direction, the laminated sheet is formed with: a functional region in which the plurality of internal electrodes are stacked in the first direction; and a cutout region in which the non-electrode forming region is laminated, the cutout region being adjacent to the functional region in the second direction, and being configured such that a thickness in the first direction gradually decreases as the cutout region is separated from the functional region in the second direction.

In the step of cutting the laminated sheet, the cut-out region is cut out.

In a region adjacent to the cut-out region of the functional region, the internal electrode is bent inward in the first direction by pressure bonding. This makes it possible to form a corner portion that is curved so as to satisfy the above-described conditions.

Effects of the invention

As described above, according to the present invention, a multilayer ceramic electronic component capable of improving reliability and a method for manufacturing the same can be provided.

Drawings

Fig. 1 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention.

Fig. 2 is a sectional view of the laminated ceramic capacitor taken along line a-a'.

FIG. 3 is a sectional view of the laminated ceramic capacitor taken along line B-B'.

Fig. 4 is a flowchart showing the method for manufacturing the multilayer ceramic capacitor.

Fig. 5 is a plan view showing a process of manufacturing the laminated ceramic capacitor.

Fig. 6 is a perspective view showing a process of manufacturing the multilayer ceramic capacitor.

Fig. 7 is a sectional view showing a process of manufacturing the laminated ceramic capacitor.

Fig. 8 is a perspective view showing a process of manufacturing the multilayer ceramic capacitor.

Fig. 9 is a perspective view showing a process of manufacturing the multilayer ceramic capacitor.

Fig. 10 is an enlarged sectional view of a part of fig. 3.

In fig. 11, (a) is a view schematically showing a cross section taken along line B-B' of the laminated ceramic capacitor, and (B) is a view schematically showing the same cross section of the laminated ceramic capacitor of the comparative example of the above embodiment.

Fig. 12 is a sectional view showing a process of manufacturing the laminated ceramic capacitor.

Description of the reference numerals

10 … … laminated ceramic capacitor (laminated ceramic electronic component)

12. 13 … … internal electrode

17 … … side edge part

18 … … capacitance forming part (function part)

19 … … cover

181 … … first straight line part

182 … … second straight line part

183 … … corner

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

In the drawings, an X axis, a Y axis, and a Z axis orthogonal to each other are appropriately shown. The X, Y and Z axes are common in all figures.

1. Structure of multilayer ceramic capacitor 10

Fig. 1 to 3 show a multilayer ceramic capacitor 10 according to an embodiment of the present invention. Fig. 1 is a perspective view of a multilayer ceramic capacitor 10. Fig. 2 is a sectional view of the laminated ceramic capacitor 10 taken along line a-a' of fig. 1. Fig. 3 is a sectional view of the laminated ceramic capacitor 10 taken along line B-B' of fig. 1.

The laminated ceramic capacitor 10 includes a ceramic main body 11, a first external electrode 14, and a second external electrode 15. Typically, the ceramic body 11 has two main surfaces facing the Z-axis direction, two end surfaces facing the X-axis direction, and two side surfaces facing the Y-axis direction. For example, the ridge 11d connecting the surfaces of the ceramic body 11 is rounded. The dimension (length) in the X-axis direction, the dimension (width) in the Y-axis direction, and the dimension (height) in the Z-axis direction of the multilayer ceramic capacitor 10 are, for example, 0.25mm, 0.125mm, and 0.125mm in length, 0.4mm, 0.2mm in width, and 0.2mm in height, 0.6mm in length, 0.3mm in width, and 0.3mm in height, 1.0mm in length, 0.5mm in width, and 0.5mm in height, or 1.6mm in length, 0.8mm in width, and 0.8mm in height, respectively. Further, the dimension of the laminated ceramic capacitor 10 in the X axis direction is the dimension of the largest portion in the X axis direction, the dimension of the laminated ceramic capacitor 10 in the Y axis direction is the dimension of the largest portion in the Y axis direction, and the dimension of the laminated ceramic capacitor 10 in the Z axis direction is the dimension of the largest portion in the Z axis direction. In addition, each dimension includes a tolerance of at most 10% of each dimension on the positive side and the negative side.

The

external electrodes

14 and 15 cover the end faces of the ceramic body 11 and face each other in the X-axis direction through the ceramic body 11. The

external electrodes

14 and 15 extend from the end faces of the ceramic body 11 to the main face and the side faces. Thus, the

external electrodes

14 and 15 have a U-shaped cross section parallel to the X-Z plane and a U-shaped cross section parallel to the X-Y plane. The shapes of the

external electrodes

14 and 15 are not limited to those shown in fig. 1.

The

external electrodes

14 and 15 are formed of a good electrical conductor. Examples of the good electrical conductor forming the

external electrodes

14 and 15 include metals or alloys containing copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), and the like as a main component.

The ceramic main body 11 has a laminated body 16 and a side edge portion 17. The laminate 16 has two end faces 16a facing the X-axis direction, two side faces 16b facing the Y-axis direction, and two main faces 16c facing the Z-axis direction.

The side edge portions 17 cover both side surfaces 16b of the stacked body 16, respectively, and cover the capacitance forming portion 18 from the Y-axis direction. The thickness dimension of the side edge portion 17 in the Y axis direction can be, for example, 15 μm or less, and more preferably 12 μm or less. This can reduce the size and increase the capacitance of the multilayer ceramic capacitor 10. The thickness dimension of the side edge 17 in the Y axis direction can be set to, for example, 10 μm or more. This ensures moisture resistance of the multilayer ceramic capacitor 10. The thickness dimension of the side edge 17 in the Y axis direction is set to be the largest dimension in the Y axis direction from the side surface of the ceramic main body 11 facing the Y axis direction to the side surface 16b of the laminated body 16.

The laminated body 16 includes a capacitor forming portion 18 and a covering portion 19 covering the capacitor forming portion 18 from the Z-axis direction. The capacitor-forming portion 18 has a first internal electrode 12 and a second internal electrode 13 laminated in the Z-axis direction with a ceramic layer interposed therebetween. The capacitance forming portion 18 constitutes a functional portion of the present embodiment.

The

internal electrodes

12, 13 are each configured in a sheet shape extending along the X-Y plane. The first inner electrode 12 extends to one end surface 16a in the X-axis direction and is connected to the first outer electrode 14. The second internal electrode 13 extends to the other end face 16a in the X-axis direction and is connected to the second external electrode 15. Thus, when a voltage is applied between the first external electrode 14 and the second external electrode 15, a voltage is applied to the ceramic layers between the first internal electrode 12 and the second internal electrode 13, and a charge corresponding to the voltage can be stored in the capacitor formation portion 18.

The

internal electrodes

12 and 13 are formed of good electrical conductors. Typical examples of the good electrical conductors forming the

internal electrodes

12 and 13 include nickel (Ni), and in addition, metals or alloys containing copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), or the like as a main component.

In the ceramic body 11, a dielectric ceramic having a high dielectric constant is used in order to increase the capacitance of each ceramic layer between the

internal electrodes

12 and 13. The dielectric ceramic having a high dielectric constant includes, for example, barium titanate (BaTiO)₃) A typical perovskite-structured material containing barium (Ba) and titanium (Ti).

In addition, the ceramic layer may be made of strontium titanate (SrTiO)₃) Calcium titanate (CaTiO)₃) Magnesium titanate (MgTiO)₃) Calcium zirconate analog (CaZrO)₃) Class i, calcium zirconium titanate (Ca (Zr, Ti) O₃) Barium zirconate like (BaZrO)₃) Titanium oxide (TiO)₂) Class, etc.

The covering portion 19 and the side edge portion 17 are formed of an insulating ceramic, but may include a dielectric ceramic used for the capacitor forming portion 18, for example. This can suppress internal stress that may occur between the covering portion 19 and the side edge portion 17 and the capacitor forming portion 18.

The

internal electrodes

12 and 13 are formed over the entire width of the capacitor-forming portion 18 in the Y-axis direction, and the

peripheral portions

12b and 13b in the Y-axis direction are disposed on both side surfaces 16b of the laminate 16. In the present embodiment, the

peripheral portions

12b and 13b of the

internal electrodes

12 and 13 have shapes curved inward in the Z-axis direction. The

peripheral portions

12b and 13b of the

internal electrodes

12 and 13 tend to be bent more inward in the Z-axis direction as they are arranged outward in the Z-axis direction. Details of the curved shape will be described later.

The "inside in the Z-axis direction" refers to a direction approaching a virtual plane bisecting the multilayer ceramic capacitor 10 in the Z-axis direction, and the "outside in the Z-axis direction" refers to a direction away from the virtual plane.

The multilayer ceramic capacitor 10 having the

peripheral edge portions

12b, 13b of the bent

internal electrodes

12, 13 can be manufactured by, for example, the following manufacturing method.

2. Method for manufacturing multilayer ceramic capacitor 10

Fig. 4 is a flowchart showing a method for manufacturing the multilayer ceramic capacitor 10. Fig. 5 to 9 schematically illustrate a process for manufacturing the multilayer ceramic capacitor 10. Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described with reference to fig. 4 and fig. 5 to 9 as appropriate.

2.1 step S01: laminated ceramic sheet

In step S01, the first ceramic sheet 101 and the second ceramic sheet 102 for forming the capacitance forming portion 18, and the third ceramic sheet 103 for forming the covering portion 19 are prepared and laminated.

The

ceramic sheets

101, 102, 103 are formed as unfired dielectric green sheets containing a dielectric ceramic as a main component. The

ceramic sheets

101, 102, 103 are formed into a sheet shape using, for example, a roll coater (roll coater), a doctor blade (sector blade), or the like. The thickness of the

ceramic sheets

101, 102, 103 can be adjusted as appropriate.

Fig. 5 is a top view of the

ceramic plates

101, 102. In this stage, the

ceramic sheets

101 and 102 are formed as large sheets that are not singulated. Fig. 5 shows cutting lines Lx1, Lx2, Ly1, Ly2 when each of the multilayer ceramic capacitors 10 is singulated. The cutting lines Lx1 and Lx2 are parallel to the X axis, and the cutting lines Ly1 and Ly2 are parallel to the Y axis. The intermediate line Lc is an imaginary line extending at a position bisecting between the adjacent cutting lines Lx1, Lx 2.

As shown in fig. 5, an unfired first inner electrode 112 corresponding to the first inner electrode 12 is formed on the first ceramic sheet 101, and an unfired second inner electrode 113 corresponding to the second inner electrode 13 is formed on the second ceramic sheet 102. Although not shown in fig. 5, no internal electrode is formed on the third ceramic sheet 103 corresponding to the covering portion 19.

The

internal electrodes

112 and 113 can be formed by applying an arbitrary conductive paste to the

ceramic sheets

101 and 102. The method of applying the conductive paste can be arbitrarily selected from known techniques. For example, a screen printing method or a gravure printing method can be used for applying the conductive paste.

In the first ceramic sheet 101, a first row in which the internal electrodes 112 extending across the cutting line Ly1 are arranged in the X axis direction and a second row in which the internal electrodes 112 extending across the cutting line Ly2 are arranged in the X axis direction are alternately arranged in the Y axis direction. In the first row, the internal electrodes 112 adjacent to each other in the X-axis direction face each other with the cut line Ly2 interposed therebetween. In the second row, the internal electrodes 112 adjacent to each other in the X-axis direction face each other with the cut line Ly1 interposed therebetween. That is, the internal electrodes 112 in the first and second rows adjacent to each other in the Y-axis direction are arranged offset by one chip in the X-axis direction. The first inner electrodes 112 are arranged in the Y axis direction with an intermediate line Lc interposed therebetween. The Y-axis direction outer edge of each first internal electrode 112 extends along the cutting lines Lx1, Lx 2.

The internal electrodes 113 on the second ceramic sheet 102 are also configured in the same manner as the internal electrodes 112. In the second ceramic sheet 102, the internal electrodes 113 of the column corresponding to the first column of the first ceramic sheet 101 extend across the cutting line Ly2, and the internal electrodes 113 of the column corresponding to the second column of the first ceramic sheet 101 extend across the cutting line Ly 1. That is, the internal electrodes 113 are formed so as to be shifted from the internal electrodes 112 by one chip in the X-axis direction and the Y-axis direction. The second inner electrodes 113 are arranged in the Y axis direction with an intermediate line Lc interposed therebetween. The Y-axis direction outer edge of each second internal electrode 113 extends along the cutting lines Lx1, Lx 2.

In the first ceramic sheet 101, the non-electrode forming region N1 where the internal electrodes 112 are not applied is formed in a lattice shape on the intermediate line Lc and the cutting line Ly 2. Similarly, in the second ceramic sheet 102, the non-electrode forming region N2 where the internal electrodes 113 are not applied is formed in a lattice shape on the intermediate line Lc and the cut line Ly 1. That is, the non-electrode forming regions N1 and N2 are overlapped with each other on the intermediate line Lc between the cutting lines Lx1 and Lx 2.

These

ceramic sheets

101, 102, and 103 are laminated as shown in fig. 6 to produce a laminated sheet 104. Specifically, the first ceramic sheet 101 and the second ceramic sheet 102 are alternately laminated, and the third ceramic sheet 103 is laminated on the upper and lower sides in the Z-axis direction of the laminated body of the

ceramic sheets

101, 102. In the example shown in fig. 6, the third ceramic sheets 103 are laminated every 4 sheets, but the number of sheets of the third ceramic sheets 103 can be changed as appropriate.

2.2 step S02: crimping

In step S02, the laminated sheet 104 is pressed from the Z-axis direction.

Fig. 7 is a schematic cross-sectional view of the laminated sheet 104 viewed from the X-axis direction, illustrating the pressure bonding step of step S02.

In the pressure bonding step of this step, the pair of pressure plates S1 are opposed to each other with the laminated sheet 104 interposed therebetween in the Z-axis direction, and the laminated sheet 104 is pressure bonded by pressing these pressure plates S1 against the laminated sheet 104. The pressing plate S1 is pressed by, for example, hydrostatic pressing or uniaxial pressing.

Further, an elastic sheet S2 is disposed between the pressing plate S1 and the laminate sheet 104. The elastic sheet S2 is made of a sheet-like elastic body and is formed of, for example, polyethylene terephthalate (PET) resin. The elastic sheet S2 is pressed against the laminate sheet 104 by the pressing plate S1.

In the laminate sheet 104, a capacitor forming region (functional region) 105 in which both the

internal electrodes

112 and 113 are laminated and a cut-out region 106 in which both the non-electrode forming regions N1 and N2 are laminated are formed. The capacitor forming region 105 corresponds to the capacitor forming portion 18 and the covering portion 19 covering the upper and lower portions thereof. The cut-out region 106 is a region adjacent to the capacitance forming region 105 in the Y-axis direction where the

internal electrodes

112 and 113 are not stacked. That is, the cut-out region 106 is a region sandwiched by the dicing lines Lx1 and Lx2, and is cut out in a dicing step described later.

By providing the elastic sheet S2 and pressing the laminated sheet 104, as described below, the cut-out region 106 can be formed in a shape that sinks inward in the Z-axis direction.

As shown in fig. 12, the elastic piece S2 is formed to have a region S21 of the crimp capacitance forming region 105 and a region S22 of the crimp cut-out region 106, and the region S22 is thicker in the Z-axis direction than the region S21. The surface of the region S22 facing the laminate sheet 104 protrudes in the Z-axis direction from the surface of the region S21 facing the laminate sheet 104. The cross section in the Y-Z plane of the convex portion of the region S22 is constituted substantially rectangular. A height difference is formed between the region S22 and the region S21, for example. The difference (dimension) between the thicknesses in the Z-axis direction of the region S22 and the region S21 is Z. The region S22 is disposed so as to face the Y-axis direction center of the cutout region 106. The Y-axis direction size of the region S22 is defined as Y. In the capacitor forming region 105, the

ceramic sheets

101 and 102 having the

internal electrodes

112 and 113 formed thereon are laminated without a gap. Thereby, the capacitor forming region 105 is entirely extended in the X-Y plane by the crimping process and is substantially uniformly compressed. As a result, a substantially flat surface is formed on the capacitance forming region 105.

On the other hand, in the cutout region 106 before pressurization, gaps corresponding to the non-electrode forming regions N1 and N2 are formed. Further, the green sheet is more flexible and easily extended than the

internal electrodes

112 and 113. Therefore, the green sheet extending from the capacitance forming region 105 enters the gap by the pressing.

In addition, the elastic sheet S2 has a region S22 thicker than the region S21 disposed so as to face the Y-axis direction center portion of the cutout region 106, and is capable of applying a larger load to the cutout region 106 having a small thickness by elastic deformation. Thus, in the cutout region 106, the green sheets extending from the capacitor forming region 105 and the green sheets stacked before pressing extend in the X-Y plane and are pressed in the Z-axis direction. Therefore, in the cut-out region 106, the thickness between the

internal electrodes

12, 13 becomes gradually thinner as Lx1, Lx2 goes to the intermediate line Lc from the cutting line on the capacitance forming region 105 side. That is, the thickness of the cutout region 106 in the Z-axis direction gradually decreases as it is separated from the capacitance forming region 105 in the Y-axis direction. As a result, the cutout region 106 is formed so as to largely sink inward in the Z-axis direction in the vicinity of the intermediate line Lc.

As the cut-out region 106 sinks, the

peripheral portions

112b and 113b of the

internal electrodes

112 and 113 adjacent to the cut-out region 106 are also bent inward in the Z-axis direction. More specifically, the

peripheral edge portions

112b and 113b are bent by the elastic piece S2 entering the cutout region 106 receiving a force inward in the Z-axis direction. In addition, the

peripheral edges

112b and 113b can also receive a force inward in the Z-axis direction by the laminated body of the ceramic sheets 103 extending from the center portion side of the capacitance forming region 105. Thereby, the curved

peripheral portions

112b and 113b are formed on the

internal electrodes

112 and 113. The

inner electrodes

112 and 113 located on the outer sides in the Z-axis direction are more likely to be subjected to a force toward the inner sides in the Z-axis direction, and therefore bend more than toward the inner sides in the Z-axis direction.

2.3 step S03: cutting of

In step S03, the laminate sheet 104 pressure-bonded in step S02 is cut along the dicing lines Lx1, Lx2, Ly1, Ly2, thereby producing an unfired laminated chip 116 shown in fig. 8. The laminated chip 116 corresponds to the fired laminate 16. For cutting the laminate sheet 104 in this step, for example, a press cutter or a rotary cutter can be used.

In fig. 8 to 9, the regions outside the

peripheral edge portions

112b and 113b on the main surface facing the Z-axis direction are substantially flat, but in reality, the regions are curved inward in the Z-axis direction similarly to the

peripheral edge portions

112b and 113 b.

When the cutting lines Lx1 and Lx2 are cut with a pressure cutter, the width of the cutter is relatively narrow, and therefore the cutter can be brought into contact with the cutting lines Lx1 and Lx2 to cut. Thus, the laminated sheet 104 is cut along the cutting lines Lx1 and Lx2, and the cut-out regions 106 between the cutting lines Lx1 and Lx2 are removed, whereby the laminated chips 116 can be formed.

When the cutting lines Lx1, Lx2 are cut with the rotary knife, the knife is in contact with the entire cut-out region 106 including the cutting lines Lx1, Lx2 because the knife has a relatively wide width. Thus, the cut-out region 106 is cut out by the rotary knife, and the stacked chips 116 can be formed.

As shown in fig. 8, in the laminated chip 116, side surfaces 116b are formed as cut surfaces corresponding to the dicing lines Lx1 and Lx 2. The

peripheral edges

112b and 113b of the

internal electrodes

112 and 113 are exposed from the side surface 116 b. The

peripheral portions

112b, 113b are curved inward in the Z-axis direction as they approach the side surface 116 b. On the other hand, in the laminated chip 116, the end face 116a is formed as a cut corresponding to the dicing lines Ly1, Ly 2. One of the

internal electrodes

112 and 113 is exposed from the end surface 116 a.

More specifically, the stacked chip 116 includes: an unfired capacitor forming portion 118 corresponding to the capacitor forming portion 18; and an unfired cover portion 119 corresponding to the cover portion 19. In capacitor forming portion 118, both

internal electrodes

112 and 113 are alternately stacked between green sheets corresponding to ceramic layers. In the capacitor forming portion 118, the

peripheral portions

112b and 113b of the

internal electrodes

112 and 113 are bent, and thus the cross section of the capacitor forming portion 118 as viewed from the X-axis direction is formed in a rectangular shape with rounded corners.

2.4 step S04: side edge formation

In step S04, unfired side edge portions 117 are formed on the side surfaces 116b of the laminated chip 116 obtained in step S03 where the

internal electrodes

112 and 113 are exposed. This produces an unfired ceramic body 111 as shown in fig. 9.

The side edge portion 117 contains an unfired ceramic material, specifically, is formed of a ceramic sheet or ceramic slurry. The side edge portion 117 can be formed by, for example, attaching a ceramic sheet to the side surface 116b of the laminated chip 116. The side edge portion 117 may be formed by applying a ceramic paste to the side surface 116b of the laminated chip 116 by, for example, coating or dipping.

2.5 step S05: firing

In step S05, the unfired ceramic body 111 obtained in step S04 is fired. The firing temperature in step S05 can be determined based on the sintering temperature of the ceramic main body 111. Further, firing can be performed, for example, under a reducing atmosphere or under an atmosphere of low oxygen partial pressure.

2.6 step S06: roller grinding

In step S06, the fired ceramic body 111 is barrel-polished. The barrel polishing is performed by, for example, enclosing a plurality of ceramic bodies 111 in a barrel polishing container and rotating or vibrating the barrel polishing container. The grinding medium or liquid may be enclosed in a barrel mill container together with the plurality of ceramic bodies 111. Thus, the ridge 11d connecting the surfaces of the ceramic body 111 is chamfered, thereby producing the ceramic body 11 shown in fig. 1 to 3.

The barrel polishing in step S06 may be performed on the ceramic body 111 before firing. That is, the barrel polishing in step S06 may be performed before the firing step in step S05.

2.7 step S07: forming external electrodes

In step S07, the

external electrodes

14 and 15 are formed on both ends of the ceramic body 11 in the X axis direction obtained in step S06. The method of forming the

external electrodes

14 and 15 in step S07 can be arbitrarily selected from known methods. Thus, the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3 is formed.

Further, a part of the processing in step S07 may be performed before step S05. For example, before step S05, an unfired electrode material may be applied to both end surfaces of the unfired ceramic element 111 in the X-axis direction, and the unfired electrode material may be fired at the same time as the unfired ceramic element 111 in step S05 to form the underlying layers of the

external electrodes

14 and 15. Alternatively, the ceramic body 111 subjected to binder removal treatment may be simultaneously fired after applying an unfired electrode material thereto.

In this way, the multilayer ceramic capacitor 10 is produced. In this manufacturing method, since the side edge portion 17 is added after the side surface 16b of the laminated body 16 where the

internal electrodes

12 and 13 are exposed, the positions of the ends of the plurality of

internal electrodes

12 and 13 in the ceramic body 11 in the Y axis direction are aligned in the Z axis direction with a deviation of 0.5 μm or less.

In addition, curved

peripheral portions

12b and 13b corresponding to the

peripheral portions

112b and 113b are formed on the fired

internal electrodes

12 and 13. The

peripheral portions

12b and 13b form the capacitor-forming portion 18 having a cross-sectional shape as described below.

3. Detailed structure of capacitor forming portion 18

The capacitor forming portion 18 is formed in a rectangular shape with rounded corners in a cross section (a cross section along line B-B') perpendicular to the X-axis direction at a position bisecting the capacitor forming portion 18 in the X-axis direction. Hereinafter, the cross section along the line B-B 'will be referred to as "B-B' cross section".

As shown in fig. 3, the capacitance forming portion 18 has, in the cross section: two first straight portions 181 adjacent to the covering portion 19 and extending in the Y-axis direction; two second straight portions 182 adjacent to the side edge portions 17 and extending in the Z-axis direction; and 4 corner portions 183 connected to the first and second

linear portions

181 and 182. The two first linear portions 181 face each other in the Z-axis direction, and the two second linear portions 182 face each other in the Y-axis direction.

In the B-B' cross section, the capacitance forming portion 18 is configured substantially line-symmetrically with respect to the Y-axis direction and the Z-axis direction. Therefore, the structure of the one corner portion 183 and the first and second

straight portions

181 and 182 connected thereto will be described in detail below with reference to fig. 10, which is an enlarged sectional view of fig. 3.

As shown in fig. 10, the first straight portion 181 is a straight portion extending in the Y-axis direction, and is formed by the outermost

internal electrodes

12 and 13 in the Z-axis direction. The first straight line portion 181 may be substantially straight, and may be, for example, meandering, curved, or the like in the Z-axis direction within a very small range of 1% or less of the height dimension of the ceramic main body 11 in the Z-axis direction.

The outermost

internal electrodes

12 and 13 are the outermost internal electrodes E. The outermost internal electrode E includes: a flat portion E1 constituting the first straight portion 181; and a peripheral edge portion E2 located at the Y-axis direction peripheral edge of the flat portion E1 and bent inward in the Z-axis direction from the flat portion E1. The flat portion E1 may be substantially flat, and may have irregularities in the Z-axis direction within an extremely small range of, for example, 1% or less of the height dimension of the ceramic main body 11 in the Z-axis direction.

An end point P1 of the first straight line portion 181 is located at a boundary between the flat portion E1 and the peripheral portion E2.

The second linear portion 182 is a linear portion extending in the Z-axis direction, and is formed by the side surface 16b of the laminated body 16. The second linear portion 182 may be substantially linear, and may be, for example, meandering, curved, or the like in the Y-axis direction within an extremely small range of 0.5% or less of the width dimension of the ceramic main body 11 in the Y-axis direction.

The end point P2 of the second linear portion 182 is defined by the Y-axis direction tip Ea2 of the peripheral edge E2 of the outermost internal electrode E.

The corner portion 183 is a curved portion connecting an end point P1 of the first linear portion 181 and an end point P2 of the second linear portion 182. The corner 183 is formed by the peripheral edge E2 of the outermost internal electrode E. The corner portion 183 curves inward in the Z-axis direction as going from the end point P1 of the first linear portion 181 to the end point P2 of the second linear portion 182.

The shape of the corner 183 is defined by the following values of a and a/b. a is a value corresponding to the height dimension of the corner 183 in the Z-axis direction, and b is a value corresponding to the length dimension of the corner 183 in the Y-axis direction. This can define a preferable shape of the corner 183.

More specifically, a is a distance in the Z-axis direction between a first imaginary line L1 extending from the first straight line portion 181 and an end point P2 of the second straight line portion 182 on the first imaginary line L1 side. The value of a can be controlled by the number of lamination of the

ceramic sheets

101 and 102, the thickness of the

ceramic sheets

101 and 102, and the like. Alternatively, the value of a may be controlled by the modulus of elasticity of the elastic piece S2, the load of the pressure plate S1, or the like in the pressure bonding step of step S02 described above.

B is a distance in the Y axis direction between a second imaginary line L2 extending from the second straight portion 182 and an end point P1 of the first straight portion 181 on the second imaginary line L2 side. The value of b can be controlled by the number of lamination of the

ceramic sheets

101 and 102, the thickness of the

ceramic sheets

101 and 102, and the like, and can also be controlled by the elastic modulus of the elastic sheet S2, the load of the pressing plate S1, and the like in the above-described crimping step of step S02. For example, referring to fig. 12, when the dimension Y of the region S22 in which the elastic sheet S2 is thickened in the region facing the cutout region 106 is increased in the Y-axis direction, the value b can be increased; when the dimension Y of the region S22 in which the elastic sheet S2 is thickened is reduced in the Y-axis direction, the b value can be reduced. The dimension Y is adjusted to be 15% to 95% of the dimension yw of the cutout region 106 in the Y-axis direction. In addition, when the thickness Z of the region S22 in which the elastic sheet S2 is thickened in the region facing the cutout region 106 is increased in the Z-axis direction, the value a can be increased; when the thickness Z of the region S22 in which the elastic sheet S2 is thickened is reduced in the Z-axis direction, the value a can be reduced. The dimension Z is preferably adjusted to be 5% to 40% of the thickness of the laminated sheet 104 before pressure bonding in the Z-axis direction. When the ratio of the dimension z to the dimension y of the elastic sheet S2 is obtained, the a/b value can be increased when the z/y is increased, and the a/b value can be decreased when the z/y is decreased.

The corner 183 is curved so as to satisfy the condition that a is not less than 1 μm and a/b is not less than 0.1 and not more than 0.4.

In the above conditions, the corner 183 satisfies a.gtoreq.1 μm and a/b.gtoreq.0.1, whereby the peripheral edge E2 of the outermost internal electrode E can be sufficiently bent, and the moisture resistance can be improved as described below.

Fig. 11 (a) is a view schematically showing a cross section B-B' of the ceramic body 11 of the present embodiment, and the region occupied by the capacitance forming portion 18 is surrounded by a broken line. Fig. 11 (B) is a diagram schematically showing a cross section B-B' of the ceramic main body 21 of the comparative example of the present embodiment, and the region occupied by the capacitance forming portion 28 is surrounded by a broken line.

In the ceramic

main bodies

11 and 21, the

ridge portions

11d and 21d are typically chamfered from the viewpoint of preventing chipping and the like. Therefore, the

ridge portions

11d, 21d of the ceramic

main bodies

11, 21 are formed with rounded corners.

In the ceramic main body 21 of the comparative example shown in fig. 11 (B), the peripheral edge portion in the Y axis direction of the internal electrode of the capacitor-forming portion 28 is not rounded, and therefore the cross-sectional shape of the capacitor-forming portion 28 is formed in a substantially rectangular shape. That is, the capacitance forming portion 28 includes a first straight portion 281 extending in the Y axis direction, a second straight portion 282 extending in the Z axis direction, and a corner portion 283 bent at substantially right angle.

Thus, in the ceramic body 21, the distance from the rounded ridge portion 21d of the surface to the corner portion 283 formed by the end of the outermost internal electrode is likely to be reduced. Therefore, particularly when the side edge portion 27 is formed thin in the Y-axis direction, the distance between the ridge portion 21d and the outermost internal electrode becomes small. Therefore, moisture easily enters from the vicinity of the ridge portion 21d, and the moisture resistance is lowered.

On the other hand, in the ceramic body 11 of the present embodiment shown in FIG. 11A, the capacitor-forming portion 18 includes a corner 183 curved so that a.gtoreq.1 μm and a/b.gtoreq.0.1 are satisfied. This can sufficiently secure the distance from the ridge 11d of the ceramic main body 11 to the peripheral edge E2 of the outermost internal electrode E. Therefore, the moisture resistance can be suppressed from being lowered with the thinning of the side edge portion 17.

Further, referring to FIG. 10, by making the corner 183 satisfy a.gtoreq.1 μm, a sufficient distance from the principal surface 16c to the tip Ea2 of the outermost internal electrode E can be ensured. In the present embodiment, since the side edge 17 is added later, the boundary portion between the stacked body 16 and the side edge 17 is likely to be a moisture entry path. On the other hand, in the present embodiment, the distance in the Z-axis direction from the boundary portion between the main surface 16c and the side edge 17 to the tip Ea2 can be increased according to the value of a. Therefore, by setting the corner 183 to satisfy a ≧ 1 μm, the distance can be sufficiently secured, and the moisture resistance against the entry of moisture from the main surface 16c side can be improved.

Further, by making the corner 183 satisfy the condition that a/b is 0.4 or less, the peripheral edge portion E2 of the outermost internal electrode E can be prevented from being bent too sharply in the Z-axis direction. As described above, the

peripheral portions

12b and 13b of the

internal electrodes

12 and 13 tend to curve sharply inward in the Z-axis direction as they are arranged outward in the Z-axis direction. Therefore, when the outermost internal electrode E is sharply bent, the peripheral edge portion E2 may contact the

peripheral edge portions

12b and 13b adjacent in the Z-axis direction, and short-circuit may occur. By making the corner 183 satisfy the condition of a/b ≦ 0.4, the bending of the peripheral edge portion E2 can be appropriately alleviated, and short-circuiting due to contact between the

internal electrodes

12, 13 can be prevented.

As described above, according to the multilayer ceramic capacitor 10 of the present embodiment, moisture resistance can be improved, a short circuit between the

internal electrodes

12 and 13 can be suppressed, and reliability can be improved.

The present embodiment will be further described below with reference to examples.

4. Examples of the embodiments

As examples and comparative examples of the present embodiment, samples of multilayer ceramic capacitors having capacitance forming portions with various cross-sectional shapes were produced, and reliability was examined. In these samples, the dimension in the X-axis direction was set to 1.0mm, and the dimensions in the Y-axis direction and the Z-axis direction were set to 0.5 mm. The thickness of the side edge portion in the Y-axis direction was set to 10 μm.

Table 1 shows values of a and b at the corner of the capacitor-forming portion, which are measured in the samples of the laminated ceramic capacitor according to the comparative examples, and a/b value calculated from these values. The values shown in table 1 are average values of 1000 samples in each example and comparative example. The values of a and B at the corner portions were determined by dividing the capacitor-forming portion of each sample in half in the X-axis direction, polishing the capacitor-forming portion to expose a cross section along the line B-B', and then confirming the values at 3000 to 30000 times with a Scanning Electron Microscope (SEM).

TABLE 1

a is a value corresponding to the height dimension of the corner in the Z-axis direction. Specifically, as shown in fig. 10, a is a distance in the Z-axis direction between a first virtual line (L1) extending from the first straight line portion (181) and an end point (P2) of the second straight line portion (182) on the side of the first virtual line (L1). The value of a was adjusted so that the value shown in table 1 was obtained by adjusting the dimension z of the region S22 in which the elastic sheet S22 was thickened.

b is a value corresponding to the length of the corner in the Y-axis direction. Specifically, b is defined as the distance in the Y-axis direction between a second imaginary line (L2) formed by extending the second linear portion (182) and an end point (P1) of the first linear portion (181) on the side of the second imaginary line (L2), as shown in fig. 10. The value of b was adjusted so as to be the value shown in table 1 by adjusting the dimension y of the region S22 in which the elastic sheet S2 was thickened.

As shown in Table 1, the corner portions of the samples of examples 1 to 4 all satisfy the conditions that a.gtoreq.1 μm and a/b is 0.1. ltoreq.0.4.

On the other hand, the sample of comparative example 1 had a of 0.2 μm and a/b of 0.01, and the conditions of a.gtoreq.1 μm and a/b.gtoreq.0.1 were not satisfied.

In addition, the sample of comparative example 2 had a of 1 μm, but had a/b of 0.03, and the condition that a/b.gtoreq.0.1 was not satisfied.

The samples of comparative examples 3 to 8 all had a/b values of 0.50 or more, and did not satisfy the condition that a/b was not more than 0.4.

The moisture resistance deterioration rate was examined for 1000 samples of examples 1 to 4 and comparative examples 1 to 8. The moisture deterioration resistance was calculated from the ratio of the number of samples having an insulation resistance of less than 1M Ω, by measuring the insulation resistance after applying a voltage 2 times the rated voltage at a temperature of 85 ℃ and a humidity of 85% for 100 hours.

In examples 1 to 4 and comparative examples 3 to 8 in which the corner portions satisfy the conditions of a.gtoreq.1 μm and a/b.gtoreq.0.1, the moisture resistance deterioration rate was 0.0% and both had sufficient moisture resistance.

On the other hand, in comparative example 1 in which a was 0.2 μm and a/b was 0.01, it was confirmed that the moisture resistance deterioration rate was 0.5%, and the moisture resistance was inferior to that of example.

In comparative example 2 where a was 1.0 μm and a/b was 0.03, the moisture resistance deterioration rate was 0.1%, and the moisture resistance was slightly inferior to that of example.

Next, the short-circuit defect rate of each sample was evaluated. The short-circuit defect rate was evaluated by using an LCR meter under the condition that a voltage of 0.5V Osc (catalysis level) and 1kHz frequency was applied. For each sample, 100 evaluations were performed by random selection, and the ratio of the number of short-circuited samples out of 100 was defined as the short-circuit defect rate.

As a result, in examples 1 to 4 and comparative examples 1 and 2 satisfying a/b of 0.4 or less, the short-circuit defect rate was 0%. Therefore, in examples 1 to 4 satisfying the above conditions, it was confirmed that the peripheral edge portions of the internal electrodes are less sharply bent as they come into contact with the adjacent internal electrodes, and short-circuiting can be prevented.

On the other hand, in comparative examples 3 to 8 in which the a/b ratio was larger than 0.4, the short-circuit defect rate was 1% or more. In particular, the short-circuit defect rate tends to increase as a/b increases. From the results, it was confirmed that short-circuiting can be reliably suppressed by suppressing a/b to 0.4 or less.

As described above, it was confirmed that examples 1 to 4 having corner portions satisfying the conditions of a.gtoreq.1 μm and a/b.ltoreq.0.1.ltoreq.0.4 all had a highly reliable structure having high moisture resistance and suppressed short circuit. In addition, it was confirmed that in the case where the corner portion of the sample in which the dimension in the X-axis direction of the laminated ceramic capacitor was 0.2mm and the dimensions in the Y-axis direction and the Z-axis direction were 0.125mm, and the sample in which the dimension in the X-axis direction of the laminated ceramic capacitor was 1.6mm and the dimensions in the Y-axis direction and the Z-axis direction were 0.8mm, the conditions of a.gtoreq.1 μm and 0.1. ltoreq. a/b.ltoreq.0.4 were satisfied, the structure was highly reliable in that the moisture resistance was high and the short circuit was suppressed.

5. Other embodiments

While the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention.

In the above-described embodiment, the multilayer ceramic capacitor 10 was described as an example of the multilayer ceramic electronic component, but the present invention can be applied to all multilayer ceramic electronic components having a ceramic body in which internal electrodes are laminated. Examples of such a multilayer ceramic electronic component include chip varistors, chip thermistors, multilayer inductors, and the like.

Claims

1. A laminated ceramic electronic component, comprising:

a functional section having internal electrodes laminated in a first direction;

a covering portion that covers the functional portion from the first direction; and

covering a side edge portion of the functional portion from a second direction orthogonal to the first direction,

the functional portion has, in a cross section orthogonal to a third direction orthogonal to the first direction and the second direction where the functional portion is bisected, in a section orthogonal to the third direction: a first linear portion adjacent to the covering portion and extending in the second direction; a second straight portion adjacent to the side edge portion and extending in the first direction; and a corner portion connected to the first linear portion and the second linear portion,

the corner portion is curved so as to satisfy the condition that a is not less than 1 [ mu ] m and 0.1 is not less than 0.4, where a distance in the first direction between a first virtual line, which is formed by extending the first straight portion in the second direction, and an end point on the first virtual line side of the second straight portion is a, and a distance in the second direction between a second virtual line, which is formed by extending the second straight portion in the first direction, and an end point on the second virtual line side of the first straight portion is b.

2. The laminated ceramic electronic component according to claim 1, wherein:

the thickness of the side edge part is 10-15 μm.

3. The laminated ceramic electronic component according to claim 2, wherein:

the side edge portion has a thickness of 12 μm or less.

4. The laminated ceramic electronic component according to any one of claims 1 to 3, wherein:

the corner portion is curved inward in the first direction from the end point on the second imaginary line side of the first linear portion toward the end point on the first imaginary line side of the second linear portion.

5. The laminated ceramic electronic component according to any one of claims 1 to 4, wherein:

the functional portion has 4 of the corner portions in the cross section.

6. A method for manufacturing a laminated ceramic electronic component, comprising:

a step of laminating a third ceramic sheet, on which internal electrodes are not formed, in a first direction on an outer surface in the first direction of a laminated body in which first ceramic sheets and second ceramic sheets are alternately laminated in the first direction to produce a laminated sheet, wherein the first ceramic sheets and the second ceramic sheets are respectively formed with a plurality of internal electrodes;

a step of pressure-bonding the laminated sheet from the first direction;

a step of manufacturing a laminated chip by cutting the pressure-bonded laminated sheet, wherein the laminated chip includes: a functional portion having internal electrodes laminated in the first direction; a covering portion that covers the functional portion from the first direction; and a side surface exposed from the internal electrode and facing a second direction orthogonal to the first direction;

forming a side edge portion on the side surface; and

forming a functional portion after firing by firing the laminated chip on which the side edge portion is formed,

the fired functional part has, in a cross section orthogonal to a third direction orthogonal to the first direction and the second direction, at a position where the fired functional part is bisected in the third direction: a first linear portion adjacent to the covering portion and extending in the second direction; a second straight portion adjacent to the side edge portion and extending in the first direction; and a corner portion connected to the first linear portion and the second linear portion,

7. The method of manufacturing a laminated ceramic electronic component according to claim 6, wherein:

in the first ceramic sheet and the second ceramic sheet, the plurality of internal electrodes are arranged at intervals from each other in the second direction with a non-electrode forming region interposed therebetween,

in the step of pressure-bonding from the first direction, the laminated sheet is formed with: a functional region in which the plurality of internal electrodes are stacked in the first direction; and a cutout region in which the non-electrode forming region is laminated, the cutout region being adjacent to the functional region in the second direction and configured such that a thickness in the first direction gradually decreases as the cutout region is separated from the functional region in the second direction,

in the step of cutting the laminated sheet, the cut-out region is cut out.